1. Field of the Invention
The present invention relates to an image forming apparatus for forming an image on a recording medium by discharging ink from ink discharge openings and also to its control method.
2. Description of the Related Art
An inkjet-type image forming apparatus, for example, an inkjet printer, has been widely used because of its advantages such as a low operating cost, easy colorization of a print image, and easy miniaturization of the apparatus. The inkjet printer is designed to form an image by discharging a minute amount of ink from each of fine ink discharge openings formed in corresponding ink-discharge surfaces of a print head. Unless the printer has continued a printing operation for a long time interval and hence has discharged ink from the ink discharge openings of the print head for that time interval, ink discharged during the last printing operation and accreted in the ink-discharge openings and the vicinities thereof of the ink-discharge surfaces may evaporate into high viscosity or solidification, thereby blocking ink from being discharged normally.
On this account, in the known inkjet printer, the print head is cleaned by pressing a blade made from a slightly hard rubber or the like onto the ink-discharge surfaces of the print head and by sliding the blade across the ink-discharge surfaces so as to remove (i.e., to wipe out) ink accreted on the ink-discharge surfaces with the ink having a high viscosity or been solidified. In association with this, Japanese Unexamined Patent Application Publication No. 57-34969 has disclosed a technique in which a plurality of blades are fixed to a rotating shaft and a wiping effect is improved by rotating the blades.
However, since ink accreted on the ink-discharge surfaces is wiped by pressing the blade made from a slightly hard rubber or the like onto the ink-discharge surfaces of the print head and by sliding the blade across the ink-discharge surfaces in such a known related art, a large force is exerted on the ink-discharge surfaces by the blade, thereby sometimes resulting in damaging the ink-discharge surfaces.
Also, when the above blade is used, it is expected to perform its duty depending on only its wiping effect; however, its wiping operation is not enough to solve a problem in that ink sometimes remains in the ink-discharge openings and the vicinities thereof. Even when the plurality of blades are used, the ink-discharge surfaces are sometimes damaged and also ink sometimes remains in the ink-discharge openings and the vicinities thereof in a similar fashion to the former case.